Sanitary management methods adopting the HACCP (Hazard Analysis Critical Control Point) system are beginning to be employed to ensure food safety in various kinds of food industry in recent years. Management items in the HACCP include packaging materials management, ingredient management, cooking and chilling, storage and environment management. In the cooking and chilling aspect of the management system, it has become essential to adopt the so-called Cook-Chill system. The introduction of the Cook-Chill system into meals at schools, companies, hospitals, prisons and the like, and into hotels, restaurants and the like has been deliberated upon and accepted.
In the Cook-Chill system, which is a system for cooking and low temperature storage, food that has been cooked is quickly cooled and then stored over a specific length of time in a chilled (0.degree. C.-3.degree. C.) state until it is reheated immediately before it is served. More specifically, after the food is cooked by applying a heat to raise the temperature at the core of the food to 70.degree. C. or higher for at least two minutes, the cooling process is started within 30 minutes to lower the temperature at the core of the food to 3.degree. C. or lower within 60-90 minutes. This eliminates the risk of the food staying within the temperature range (16.degree. C.-52.degree. C.) over which bacteria in the food are most likely to propagate by passing through this temperature range quickly to reach the safe temperature range. The food that has been rapidly chilled in this manner is then stored in a chilled state within the range of 0.degree. C.-3.degree. C. The food that is taken out of chilled storage is immediately heated to hold a temperature of 70.degree. C. or higher at the core of the food for two minutes or longer.
Now, in the Cook-Chill system described above, different types of cooling rooms for rapidly cooling foods must be provided dependent on the ingredients and the forms of the foods. For instance, foods with a high water content such as cooked noodles including chow mein and udon noodles and side-dishes are rapidly cooled through vacuum cooling at low temperature. In other words, by placing the food to be cooled in a vacuum state, cooling is achieved through the discharge of latent heat by vaporizing the water in the food.
In addition, dishes such as beefsteak and hamburger patties that are put on trays in a chilled state are cooled by employing a blast chiller (forced draft cooler). The blast chiller generates low-temperature air and performs cooling by directly blowing the low-temperature air at high speed with a fan onto the food. Under normal circumstances, a cooling coil is mounted on the ceiling or the like and the low-temperature air is circulated by the fan to blow against the food. Furthermore, cooling achieved through the use of a blast chiller, in which freon or the like that is at a lower temperature than brine is supplied to the cooling coil, is effective when cooling foods that need to be cooled rapidly.
Moreover, liquid foods such as soup that are placed in containers and foods that are packaged in plastic bags or through vacuum packing are cooled in a tumble chiller (chilled water cooling tank) that uses chilled water. In the tumble chiller cooling method, the ice heat storage system is normally adopted. Namely, chilled water is stored in an ice heat storage tank and the chilled water is made to circulate within the cooling tank where a packaged food or the like is stored to be cooled.
However, at facilities such as schools described earlier where the Cook-Chill system is employed, a great number of meals must be prepared each day. Installing a large vacuum cooler, a large blast chiller and a large tumble chiller to meet such broad demand, with a brine cooling means provided at each of them, causes the problem that the entire facility becomes overly large and then a large area is required for the installation of such facilities. In addition, since a heat source device must be provided for each cooler, the production cost and the power consumption will increase.
An object of the present invention, which is proposed to address the problems of the prior art discussed above, is to provide a cooling system that requires a smaller area for installation and achieves reductions in production costs and in power consumption.